Abstract

We derive expressions that allow us to examine the influence of different source parameters on the correlation of intensity fluctuations (the Hanbury Brown–Twiss effect) at two points in the same cross section of a random electromagnetic beam. It is found that these higher-order correlations behave quite differently than the lower-order amplitude-phase correlations that are described by the spectral degree of coherence.

Evolution of (a) the normalized correlation of intensity fluctuations and (b) the modulus of the spectral degree of coherence when ρ2=0.65mm. The dashed lines are the asymptotic values given by Eqs. (25) and (27), respectively.

Evolution of the normalized correlation of intensity fluctuations as a function of z for different values of the parameter δxy. From bottom to top: δxy=2.3mm (blue), 2.6 mm (red), 2.9 mm (green), and 3.2 mm (purple). As in Fig. 4, ρ2=2mm.

Evolution of (a) the normalized correlation of intensity fluctuations and (b) the modulus of the spectral degree of coherence for different choices of ρ2. From bottom to top, ρ2=1.5mm (blue), 1 mm (red), 0.5 mm (green), and 0.2 mm (purple); the dashed lines are the asymptotic values given by Eqs. (24) and (26), respectively.